Control means for differential



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T. O. MEHAN CONTROL MEANS FOR DIFFERENTIAL ACTUATORS Filed March 14. 1946 Sept. 18, 1951 Sept. 18, 1951 T. o. MEHAN CONTROL MEANS FOR DIFFERENTIAL ACTUATORS Filed March 14. 1946 5 Sheets-Sheet 5 INVENTOR. .Tfzomozs aMeJ/)z vfiiorneys.

Sept. 18, 1951 T. o. MEHAN CONTROL MEANS FOR DIFFERENTIAL ACTUATORS Filed March 14. 1946 5 Sheets-Sheet 4 Sept. 18, 1951 T. o. MEHAN 2,568,350

CONTROL MEANS FOR DIFFERENTIAL ACTUATORS Filed March 14. 1946 5 Sheets-Sheet 5 I N VEN TGR. Zf om as 0. Jde/ian OLD r|ME ELAPSED ral. *rl-lil ITEM :NT:

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Patented Sept. 18, 1951 CONTROL MEANS FOR DIFFERENTIAL ACTUATORS Thomas 0. Mehan, Park fRidge, Ill., assignor to Victor Adding Machine Co., Chicago, Ill.,.a corporation of Illinois Application March 14, 1946, Serial N o. 654,424

1 Claim.

My invention relates generallyY to calculating and adding machines, and .more particularly to improvements in means for controlling the operation of the movable actuators of such machines.

The principal object of my invention is to provide improved means to increase the overall speed of operation of a calculating or adding machine, without increasing the speed at which the mechanism of `the machine is required to operate.

Heretofore, Ain calculating or adding machines of the type employing movable actuators or sectors, a short inter-val Yof time is lost, from an ,operator.s viewpoint, for each .machine cycle due to the fact that Athe operator cannot set up a second amount in the keyboard until the machine has fully completed its cycle 'for the first amount entered.

The reasons vfor this .loss of time will be briefly explained in connection with calculating machines of the ten key type, and then in connection with machines of the full 'key type.

It is well known to those skilled in the art of calculating machines that when an amount is entered, or set up, in a ten key machine, the conventional stop pin carriage is caused to move transversely one denominational order for each key depressed, and, during the initial portion of an Voperating cycle, its stop pins are engaged by stop shoulders on the actuating racks (-or sectors) corresponding to the denominational orders set up inthe stop pin carriage. 'I'he extent of rearward travel of the lactuators will be determined by the numerical value of thekeys depressed. With this conventionalconstruction, it becomes necessary to delay the restoration of the pin carriage until after the actuatorsare restored to their home or normal position in order to avoid collision Vbetween the set stop pins of the carriage and the stop shoulders of the actuators. The return of the -stop pin carriage to its home position 'takes place near the end of the operating cycle and thus precludes the entry of a second amount in the keyboard until the end of the machine operating cycle.

When an amount isset up in a full keyboard machine, theV depending Vstems of the keys depressed -are directly engaged by the stop shoulders on the actuators, and the extent of rearward travel of the actuators will be determined by the numerical value of the keys depressed. In this conventional type of calculating machine it is necessary that the actuators be fully restored to their home positions before a second amount 'can be entered in the key board so that collision between the depending stems of the depressed keys and the vstop shoulders of the actuators is avoided, as the latter return forward near .the end of the adding cycle.

An important lobject of my invention, therefore, is to provide -new and novel means for the control of movable actuators of adding -and calculating machines so that amounts can be entered vin the keyboards of 4such machines before the .actuators or sectors are fully restored, without danger of interference or collision between the movable parts of Ithe machines.

Still further, and more limitedly, it is the purpose of my invention to permit entry of an item in a calculating or adding machine at approximately midway of .its .operating cycle. I accomplish Ythis by lowering the actuators, or the stop shoulders thereof, so that earlier restoration of the stop pin carriage and ventry ofa subsequent amount can be Vhad in vmachines of the ten key type, and earlier entry of a subsequent amount can .be had inV machines of the full key board type `before the actuators are fully restored.

The foregoing objects, and others Yhereinafter appearing, are attained in 'the embodiment of .the invention illustrated in vthe accompanying drawings, wherein:

Fig. 1 is a fragmentary longitudinal sectional view of a ten key adding machine, embodying the principles of the present invention, and showing particularly the means for -controlling the vmovable actuators which are shown in their Vnormal lowered position;

Fig. 2 is .a View similar to Fig. l, with the keyboard omitted, and showing the main shaft lmoved to mid-cycle position with the Yactuators 4locked in their elevated position;

Fig. 3 is a fragmentary isometric View clearly villustrati-ng the novel control -mechanism for the actuators;

Fig. 4 is a fragmentary plan view, with the casing and keyboard removed, and including a manually operable crank for Vdri-ving the main shaft through its forward stroke;

Fig.. 5 is a timing chart for the ten key machine shown in Figs. l 'to 4;

Fig. 6 is a fragmentary longitudinal sectional View, partly in elevation, illustrating a full keyboard machine embodying the principles of the 4present invention and showing the actuators in their normal lowered position;

Fig. 'I is a fragmentary longitudinal sectional view, similar to Fig. 6, with certain parts, such as 'the 4case and motor, omitted, and showing the actuators in elevated positions;

aseasuo Fig. 8 is a fragmentary sectional View taken on the line 8--8 of Fig. '7 and Fig. 9 is a diagrammatic chart showing the time saved during three machine cycles with a machine equipped with the present invention as compared with a conventional machine. n

Since the invention disclosed is concerned primarily with new and novel controls for adding and calculating machine actuators, only so much of the machine as is necessary for the understanding of the present invention is shown. For a further and more complete disclosure of the structural features of the ten key machine shown in the present application, reference may be had to my prior application Serial No. 566,980, led December 7, 1944, issued as Patent No. 2,486,959 on November 1, 1949, and for more structural details of the full key machine here shown, attention is invited to my prior application Serial No. 371,366, filed December 23, 1940, which has matured into Patent No. 2,411,050.

Referring now to the drawings for a detailed explanation of my invention, the invention will be described first as it may be utilized in a ten key adding or calculating machine, reference being had to Figs. 1 to 5, and 9.

In the plan view, Fig. 4, the ten key machine is shown as comprising a base I to which a pair of outer frame plates II and I2, and a pair of intermediate frame plates I3 and I4, are suitably secured. A main operating shaft I5 is mounted for rocking motion in these frame plates, and in the embodiment shown is rocked through its forward stroke by the conventional hand crank I6, and through its return stroke by a main spring I 'I. It will be understood, however, that the main shaft may be rocked by an electric motor, if

desired, since the manner in which the main shaft is driven has no effect upon the present invention.

Amounts to be entered in the machine are set up by the successive depression of the required spring-returned 0 to 9 numeral keys I8 (Fig. l), each having a depending stem I9. The lower ends of the stems I9 are in fore and aft alignment and normally lie in registry above a row of stop pins mounted in the usual manner in a stop pin carriage 2I. This carriage is transversely reciprocable, being carried by a pair of cross rails 22-23.

A plurality of actuators, shown as racks 24, one for each denominational order of the machine, and each having a stop shoulder 25, are guided for longitudinal movement by transverse rods 26 and 2l mounted in the frame plates I3 and I4, these rods passing through elongated openings or slots 28 and 29 in the actuators 24, as clearly shown in Fig. 3.

The actuators 24 are maintained in properly spaced relationvby a pair of conventional combs' 30 and 3|, and long tension springs 32 are provided to move them rearwardly, or to the right as viewed in Figs. 1 to 4.

Rack eleuating'and lowering mechanism The mechanism for elevating and lowering the racks or actuators 24 will now be described.

Referring to Fig. 3, it will be observed that transverse rod 2l is securely mounted between the frame plates I3 and I4, and serves as a fulcrum about which the actuators 24 may pivot, and that the 'ends -of transverse shaft 26 .are received by elongated slots I3.I and I4.I in the frame plates I3 and I4, respectively. A third shaft 33;

below and somewhat forward of shaft 26, is pivotally supported within the frame plates I3 and I4 and rigidly carries an arm 34 and a pair of cam plates 35, 36. The arm 3'4 is located outside the frame plate I3 and cam plate 35 is positioned inside said plate, while cam plate 36 is located just inside of frame plate I4. Arcuate slots 35.I and 36.I in the icam plates 35 and 36, respectively, receive the shaft 26 and serve to elevate and lower this shaft when the cams are rocked on their pivot shaft 33 in a manner and for reasons prese ently to be described.

The upper ends of arm 34 and cam plate 35 are joined by a stud 3'! which passes through an arcu` ate clearance slot 38 in the frame plate I3. When the arm 34 is rocked clockwise (Fig. 3), cam plates 35, 36 will also be rocked clockwise and shaft 26 will be elevated within the elongated slots lI3.I and I4.'I, in frames I3, I4 by a camming action of the slots 35.I, 36.I upon the shaft 26.

The means for rocking cam arm 34 comprises an offset link 39, one end of which is pivotally attached'to arm 34, midway of the shaft 33 and stud 31,'by a shoulder stud v34.I, and its other end has a notch 40 and inwardly projecting studs 4| land 42. These studs cooperate with a rise portion 43 on a cam plate 44, to disengage a stud 45 on the plate 44 from notch 4I] in a manner presently to be described. Pivoted upon a stud 41, projecting from the frame plate I3, is a detent lever 46 which is held inlengagement with vstud 48, projecting inwardly from link 39, by a spring 49. One end of this Aspring is anchored to a stud 50 projecting outwardly from the frame plate I3, and its other end is secured to the free endof detent lever 46, as clearly shown in Fig. 3. Link 39 is guided for longitudinal movement by a slotted bracket 5I attached to frame I3 by the stud 4'I and a screw 52.

It will now be understood, by reference to Fig. 3 and to the timing chart shown in Fig. 5, that when an operating cycle of the machine is started by crank I6, or the conventional motor 53 (Fig. 6), main shaft I5 will be rocked counterclockwise during its forward stroke by said crank or motor, and clockwise during its return stroke by the main spring I1. The construction is such that when the main shaft begins its forward stroke, cam plate 44 will be rotated counterclockwise, and its stud 45 will engage the rearward end of notch 40, thus pulling link 39 rearwardly, which in turn rocks the cam arm 34 clockwise to elevate shaft 26 in the manner heretofore explained. v

When shaft 26 is elevated, the shouldered ends 25 of actuators 24 are also elevated, or swung upon their pivot shaft 21 from the position shown in Figs. l and 3 into the position shown in Fig. 2. This elevation of the forward ends of the actuators brings their stop shoulders 25 in position to engage any stops 20 of the traveling pin carriage which may have been depressed. From the timing chart of Fig. 5, it will be noted that actuators 24 are moved from their lowered normal position to their elevated position during the first 12 of main shaft movement, and that they remain in this elevated position until the end of the forward stroke, which is shown in the chart as counterclockwis'e movement of the main shaft I5. When the end of the forward stroke is completed, and the return stroke starts, actuators 24 are again lowered, such movement taking place during the first 12 of clockwise movement imparted to the main shaft by the mais Spring' I'II it will be understood that assenso if actuators '24 :are lowered before Cthey start :their /return istroke.

'At the beginning Tof the 'return-stroke, :stud 45.I, carried by the camV yplate 44, 'will have -movediinto-notch 40:of'link139, and-:asithe-cam Splate' isrrocked clockwisethisistud will engage ftheforward. end of notch 40 to movelinkf39 Vfor- `wardly la distance suflicientto 'remove stud 48 :fromlnotch 46.2 to notch 46.1 Vof-detent lever 46. Thisiorwardmovement of link 39, cam Earm 34, and-camp'lates Y35 and36, previously described, thuslowers-'s'ha'ft 26in its frame `slots I3.`| land f4;fl, and'in turn lowers -the's'houl'derlends .'of actuators 24. This permitsthe .pin carriage 4tobe restored .immediately and permits the operatorr to enter a subsequent amount in the keyboard Yduring the'remainder of the return stroke for thelprevious amount entered.

Attention is'invited to thefact that the movement 'of cam plate`44 is considerably greater than "the movement 'of link 39, land for this reason 'it lbecomes necessary to swing .the'fre'e end of said link downwardly'to'release the studs A45 and 45.I from Athe notch 40 after they have moved the vlink from one to 'the other of its operative positions. It'will now be clear that when stud '45 -drives lthe link 39 rearwardly, its-detent stud 48 'will lbe moved from fnotch 46.I to notch 46.2 of the fdetent lever 46, and .near the end df 'this movementthe rise portion V43 of the cam plate 44 -willhave'engaged `stud 4l lto force the link downwardly fagainst the tension of Vspring 49, thereby llowering'the rearward end of said vlink 'to permit Stud -45 -to be disengaged from slot 40 during the remainder of the 4counterclockwise movement of the :cam plate `44. 'The elevated lposition of the l1nk'38`is determined by 'the depth of the slot'in bracket I. As the cam plate 4'4 approaches 'the kend of its forward or counterclockwise stroke,

lstud 45.1 'moves *into position 'in the notch 148. f

Consequently, when the return'stroke Aof the mafchine begins, stud '45.1 will move link '39 `for lwai-dlyiuntil its detent stud 48 lleaves notch v"46.2 and seats 'within notch A46.1 lof 'the detent lever `46, Aand vwhen Vthis has `taken place the lrise por- 1 Actuator or rack/locking mechanism It has been found convenient to Vprevent excesf-sive rearward motion of actuators 2`4 during Vadding and `total taking operations `where 'trans- 'fer dials (that is, numeral dials for indicating 'the 'last amount entered into the accumulator) 'are-employed, and the locking means for'accomplishing this result will now be described. With reference to Figs. 1, 2, and 4, it will be Vnoted 'that each actuator or rack has a series of saw-toothed teeth 54 cut in its 'bottom edge for'cooperation *with fthe-upwardly -bent Afingers 55 of a locking :plate 56 at the proper `-time and in a manner pres- Ientlyzto be described.

'The locking-plate 56 is rigidly attached to Iyoke portion 51 of a bail 58 in any'suit'able manner, for example, by rivets59. Arms 60 .and 6I (Fig. 4) of Ythe bail 58 are pivotally connected to depending arms f62,163 having hubs 64, A65, vrespectively, 'pinned to a shaft 66. This shaft is mounted t:for rocking movement 'in the frame plates 13, I4. Shaft' projects-outwardlybeyond the frame plate 'I3 vto 'rigidly support a Ycam -La'rm 61 which .iis f engaged `by the -stud =45.I:on cam `spla'te l44 to the flocking yfingers 55 ainto :locking engagereturn stroke of said operating cycle.

will-'befnotedthat -stud 45;| 'is 1ongerthan-stud45 sothatfthe latter lstud does-not contactthe'cam :arm 61.

alatchfplate-is tresiliently 'held in engagement with 'vatooth 12 integrally :formed-with-thelower edge f'offth'ebailarm 6|) by a spring 13 '(Figsp2 and 4) 'One'endof the spring is anchored in the spring 'plate L14 and its other'end secured to the free end "16 of -latch 69. The forward vend of bail 58 is 'supported/hva shaft 15 carried bythe arms'60, 6I ,the vends 'of this shaft being Vslidably received by inclined slots 16, 11 of plates I3 and I4, re-

speGtiVely.

Referring now .to'the'operation of the rackilock 'justvdescrib'ed it `will be noted from the chart.

of'Fig. 5, that ngers 55 remain in theposition'in which 'they are shown in Fig. l until the main lshaft is `rocked through vapproximately 100 of 'its `forward stroke. By this time stud 45.| will have engaged vthe cam face 61.| ofthe cam arm '61, whereupon ffurther movement -of the main shaft will cause said `'stud `fto 'rock the cam arm clockwise until such time as "the main shaft 'reaches approximately 117 vforward movement..

This 'clockwise movement of the cam arm 61 in 'turn 'imparts a corresponding movement to shaft 66 andthrough the karms 60, 6| moves the bail 58 to the left as viewedin'Fig. 1 and upwardly, by reason of the sha'ft 15 operating within the inclined slots 16, 11, to cause the `iingers 55 to mesh with the`teeth54 of the racks 24. This engagement of thengers55 with-the rack teeth 54 :prevents any 'further rearward movement'of the raks until sa'id iingers are disengaged. The

fingers 55 are fheld 'in engagement withthe teeth 5'4 by the latch'plate 69,`th`e inwardly turned end T0 o'f which engages behind the tooth 12 on the `bail arm 52 fand thus prevents retraction of the liingers'55'as shown'in Fig. 2.

Fro'mthe vchart shown in Fig. 5, itwill be clear that racks y.24 are locked `just prior to the end of the fforward stroke lof a machine operating cycle, and 'that lthe bail 'is'restorednear the end ofthe Such restoration of the fingers 55 to normal position is accomplished near the end of the operating cycle by the spring 13 when the stud 68 engages the latch platei69, swinging'it downwardly to move the inwardly extending portion 10 'thereof from its latching position behind the tooth 12.

Operation -In `describing the Ioperation of my improved `control for the --actuators, Ait will be recalled that transverse rod 26 normally holds said actuators in 'loweredfposition as shown `in Fig. 1, and when the-conventional trap -.door YI8 carried by the stop :pin carriageZ-I. It has -beenexplained that racks sions.

f Itis well -known to .thoserskilled inthe .art `that inten key machines, each time a numeral key |8 is depressed, its corresponding stop pin will be depressed to limit the forward movement of its associated actuator 24. Accordingly, each -time a numeral key'is depressed, the pin carriage 2| will advance one unit to theleft and trap door 18 will prevent forward motion of all actuators to the left of the highest denominational order digit entered into the keyboard.

It is also well known, in the operation of ten key machines of the prior art, that after an amount is entered in the keyboard said amount will be set up in the stop carriage, and, during the forwardstroke of the machine, one actua-tor for each digit entered is given a forward eX- cursion a distance depending upon the numerical value of the numeral key depressed, In such conventional constructions it is clear that restoration of the actuators cannot take place during the time the pin carriage is being returned to its normal right-hand position, and therefore it has been the conventional practice to delay the restoration of the pin carriage until after the actuators have been fully restored by the well known restoring bail. Thus in such prior m21-,

chines it was impossible to enter a second amount before the actuators were fully restored, due to the delay necessary for restoring the pin carriage until just prior to the end of the return stroke of a machine operating cycle.

However, according to my present invention, it is possible to start the return of the stop pin carriage after approximately 14 of the main shaft return stroke has taken place. This permits an operator to set up a second amount in the pin carriage while the actuators are being restored during the remaining portion of the return stroke of the machine cycle initiated for the iirst amount entered. This is due to the fact that while the actuators are being restored they. are held in their lowered position and thus prevent collision between theirshoulders 25 and the stop pins 20 depressed during entry of a second amount into the machine. The graphic chart, Fig. 9, shows the elapsed time required for the addition of three amounts entered in a conventional ten key machine as compared with elapsed time for the addition of three amounts entered in a ten key machine embodying my improvement. From this chart it will be observed that the time for one machine cycle is saved for each three amounts added, as compared with conventional machines.

FaZZ key machine Referring now to a detailed description of my invention, as embodied in a full keyboard machine, it will beobserved from Figs. 6 to 8 that the same general mechanism for raising and lowering the actuators is employed. It should be noted, however, thatvthe actuator racks for the` full keyboard machine are given a straight line motion when being elevated or lowered, instead of a pivotal motion in the manner described for the ten key machine. In Fig. 8 the full key machine is partially shown as comprising a base ||0 to which a pair of frame plates I and 2 respectively, are suitably secured. Mounted for rocking motion, in these plates is a main operating shaft `||5 which is rocked through the forward and return strokes of Ya machine operating cycle by a motor 53 (Fig. 6) in the conventional and well known manner. Amounts to be entered in the machine arefset up by means of the usual depressible spring return numeral keys I8, each having a depending stem ||9. The stems for each longitudinal row of keys are substantially in longitudinal alignment and their lower ends are adapted to cooperate with stop shoulders |25 formed as integral parts of actuators or racks |24. The actuators are supported by transverse U-shaped members 26, |21, and are retained in properly spaced relation by a pair oi' combs |30, |3|, the latter being secured to members |26 and |21, respectively. Each actuator |24 has a long tension spring |32 to move it rearwardly, or to the right as viewed in Figs. 6 to 8, when it is released from the conventional hook |00 through depression of any key of its associated row of keys.

Rack elevating and lowering mechanism It will be noted from Figs. 6 to 8 that the mechanism for elevating and lowering the actuators 24 comprises a cam plate |44 i'lxed to the main shaft ||5. This cam plate has outwardly projecting studs |45 and |45.| and a cam rise |43 similar to that disclosed in the ten key machine. However, the dwell portion of the cam rise |43 is considerably shorter than lthe dwell portion of cam rise 43 of the plate 44, due to the fact that main shaft |I5 of the full keyboard machine has a smaller angular movement than the main shaft l5 shown in the ten key machine. Studs |45 and |45.| alternately engage a notch |40 in one end of link |39 in a manner presently to be described, and the other end of said link is pivotally connected to a bell crank 8|. The link |39 is guided for longitudinal movement within a slot in the bracket |5|. 'An inwardly projecting stud |48 carried by the link |39 cooperates with detent lever |46 which is resiliently urged into engagement with said stud by a spring |49.

Pinned to one end of a shaft (Fig. 8) which is carried by the frame plates and ||2, is a bell crank 8| and also pinned to this shaft is a second bell crank |8|. The former bell crank is located outside the frame plate and the latter bell crank is located inside theframe plate ||2 p as clearly shown in Fig. 8. Pinned to a second shaft 83, which is also pivotally mounted in the frame plates H2, is a second pair of bell cranks 82, and |82. The downwardly projecting leg of bell cranks 8| and 82 are connected by a link 84 and consequently any movement imparted to the bell crank 8| by link |39 will cause all of said bell cranks to be rocked in unison.- Each of the bell cranks has an arm 85, and these arms of the bell cranks 8| and |8| cooperate with-the combs |30, while the arms 85 of bell cranks 82 and |82 cooperate with the comb |3|, the construction being such that when the bell cranks are rocked counterclockwise through rearward movement of link |39, combs |30, |3I', andin turn the. cross members |26, |21, will be elevated to raise actuators |24 so that their stop shoulders |25 will be in position to cooperate with any depressed key stems 9. In Fig. 6 the actuators 24 are shown in their lowered or normal position, whereas Fig. 7 illustrates'the actuators in elevated position.

Operation of fall keyboard machine From the foregoing, the obvious operation` of my improved rack movement is as follows. As

the main shaft |5 starts its counterclockwise rotation during the forward stroke of a machine operating cycle, stud |45 pulls link |39 rearwardly,

or to the right, as viewed in Fig. 6, whereupon all of the bell cranks will be rocked counterclockwise to elevate the combs |30, |3I, support members |26, |21, and the actuators |24, so that the stop shoulders |25 of said actuators are in a position to be stopped by the key stems ||9 of any keys which may have been depressed through entry of an amount set up in the keyboard. At the beginning of the return stroke of a machine operating cycle, main shaft ||5 and cam plate |44 are rocked clockwise and stud |45.|, engaging in notch |40 of link |39, will push said link forwardly, or to the left, as viewed in Fig. 6. Thus all the bell cranks will be rocked clockwise to lower the actuators |24 and cause disengagement of stop shoulders with the depending stems ||9 of any depressed digit keys ||8. At this time the springs |32 will pull the actuators |24 rearwardly to the 9 stop position, all of the racks which have been actuated, but since by this time the accumulator pinions will have been engaged, this will result merely in idle movement of the accumulator pinions each to an extent complementary to the depressed numeral key in its denominational order, compensation for such idle movement being made as the racks are restored to normal position.

The depressed keys are released in the usual and well known manner at the same time the racks are lowered, and this enables the operator immediately to enter a second item in the keyboard while the machine is completing its return stroke of the operating cycle initiated for the rst amount entered in the keyboard. Due to the fact that the actuators |24 are lowered before they start upon their return stroke, no interference or collision of the stops |25 with the stems 9 is possible, and accordingly this permits almost double speed for the operator of an electric machine since a second amount can be entered in the keyboard while the machine is completing the return stroke of the first amount entered, without waiting for the machine fully to complete its operating cycle for the first amount entered.

Electrically operated adding machines, if constructed to operate very rapidly, are noisy, wear rapidly, and are subject to troubles in service due to the misoperation of spring actuated parts. It has been found that a machine of this type operating at 120 cycles per minute represents a practical compromise between obviously desirable higher speed of operation from the users point of view and the difficulties of design, and cost of manufacture, which are reduced if the speed of operation is lowered. If the machine were to operate at speeds much higher than 120 cycles per minute, some of the parts would have to be made stronger and harder and yet lighter in weight, the spring tensions would, in general, have to be increased, the power of the motor increased, and in many of the parts manufacturing tolerances would have to be decreased, all of these conditions tending to increase the cost of the machine and tending to increase the possibility of misoperation and service troubles.

By the use of the present invention, the speed with which most adding and calculating operations may be performed is increased by 35% to 70% as compared with the speed at which such operations may be performed using a conventional machine, and this is accomplished without increasing the actual speed of operation of the machine.

Assuming a very expert operator, the machine of my invention could theoretically be operated continuously, at 120 cycles per minute, to accomplish the addition of 120 different items in one minute, whereas with a machine of the prior art capable of operating at 120 cycles per minute, it is not even theoretically possible to accomplish the addition of more than a maximum of about different items per minute.

In its broader aspects, the invention contemplates suitable means for causing the set stops to lie in the path of movement of the actuator shoulders during the rst half of the machine cycle, and after the racks have thus been positioned, relatively to move the racks and stops so that the racks may be returned to normal position without engaging the stops, and so that during the major portion of the second half of the operating cycle the stops may be reset for the entry of another item.

While I have shown and described particular embodiments of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof without departing from the more fundamental principles of the invention. I therefore desire, by the following claim, to' include within the scope of my invention all such similar and modif-led forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

In a calculating machine of the class described having a plurality of differentially movable actuators, the combination of means for raising and lowering said actuators including a main shaft; a cam fixed for movement with said main shaft, a pair of outwardly projecting studs on said cam; a pair of supporting members for said actuators one of which is movable; a pair of cam plates adapted to elevate and lower said movable support member; and means for operating said cam plates from said main shaft cam including a cam arm mounted for movement with said cam plates; a link having one end pivotally connected to said cam arm and its other end provided with a notch to successively cooperate with the studs on said main shaft cam whereby initial counterclockwise movement of said main shaft will drive said link to elevate said actuators and the initial clockwise movement of said main shaft will lower said actuators substantially as set forth and for the purposes specified.

THOMAS O. MEHAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Hellgren Dec. 1, 1942 Number 

